This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to a Japanese Patent Application 2001-040769, filed on Feb. 16, 2001, the entire content of which is incorporated herein by reference.
The present invention relates to a passenger determination device which determines the passenger on the basis of outputted load value of a load sensor attached to a seat main body.
A vehicle equipped with an air bag may be provided with a passenger determination device to determine whether a passenger is sitting on a seat or whether the seated passenger is an adult or a child. Japanese Patent Laid-Open Publication No. 9-207638 describes an example of a passenger determination device. This device includes a plurality of load sensors attached to plural portions of a seat main body and a controller for calculating a detected load value on the basis of outputted load values of the load sensors and for detecting whether a passenger is sitting on a seat. The controller adds each of the outputted load values of each load sensors by an adder and calculates the detected load value. The controller compares this detected load value with a predetermined load (a determination threshold value) by a determination processing circuit and determines on the basis of the large and small relationship between the detected load value and the threshold value whether a passenger is sitting on a seat.
However, the detected load value of the load sensors is influenced by, for example, a vibration or joggle and so on during the running of a vehicle and varies. Accordingly, in case that the weight of a passenger closes to the threshold value, the determination result is apt to be erroneously changed by the variation of the detected load value.
It is an object of the present invention to provide an improved passenger determination device which can prevent from erroneously determining a passenger due to the influence of the vibration or joggle and so on during the running of a vehicle.
In order to achieve this objective, there is provided an improved passenger determination device which includes a load sensor attached to a seat main body, a controller for calculating a detected load value on the basis of an outputted load value of the load sensor and for determining a passenger on the basis of a large and small relationship between the detected load value and a predetermined determination threshold value, a load variations detecting means for detecting variations of the detected load value when the large and small relationship between the detected load value and a predetermined determination threshold value changes and a prohibition means for prohibiting from changing the determination of the passenger by the change of the large and small relationship between the detected load value and a predetermined determination threshold value when the detected load variations is small.